I have one question. Is it possible to add a Department menu in a navigation pane in RTC ex: Administration? Not just a button to open me some object but the hole menu (to have same behavior like i open it from the Departments). Please look at the picture in attachment
No, you cannot create you navigation menu exactly as the departments menu. You can only insert “list page” objects into the navigation menu.
But still study the link Mohana gave you.
In general then you should not think of the Navigation pane as the only menu for the user. But combine it with the role centers, then you an add the objects you need to access, which are not list pages, as functions in the role center page function band or directly as items on the users role center page.